The present invention relates generally to opening arrangements for packing containers. More specifically, the present invention relates to an opening arrangement for cans of the type having at least one plane end wall made of sheet steel.
Metal cans have been used for a long time for the packing of liquid goods and depending on the resistance of the metal such cans have been used frequently for the packing of pressurized goods, such as e.g. beer and carbonated beverages.
For a long time the predominant type of cans have been those made of sheet steel, but since sheet steel has appreciable tearing resistance, often at least one end plate or lid has been manufactured from aluminium which is a softer and weaker metal making possible an accurate punching out of weakening lines along which parts of the aluminium end plate can be torn. A large number of such tearable openings in aluminium lids have been designed and the best known are probably the so-called "ring openers" which consist of a portion punched in the lid along a weakening line and a pull-ring which is riveted to the narrower part of the portion. When the said pull-ring is raised, a part of the punched out portion is torn, whereupon the remaining parts of the weakening line can be broken by pulling the pull-ring upwards.
It is one of the disadvantages of this design that it is inappropriate to mix together aluminium and steel in one and the same package, since in such a case the drum cannot be used as scrap metal, unless the aluminium parts are separated. Such a separation of the aluminium lid from the steel drum, however, is impossible economically. A known solution of the problem consists in manufacturing a drum wholly from sheet steel with a hole being provided in the sheet steel lid. Into the hole a cap of plastic material can then be inserted, and since the plastic material can easily be burnt, the remaining drum may be used as scrap metal in the manufacture of steel.
Such a solution is relatively expensive, though, and a clear need exists for a simple and inexpensive opening arrangement on a can which is completely made of sheet steel. A solution of this problem is provided in accordance with the present invention in which two tongues are provided in a steel can lid.
Each of the tongues is delimited partly by a preferably U-shaped punched line along which the lid is fully punched through and partly by a straight base line imagined between the end points of the U-shaped punched line along which the tongues are connected with the sheet steel material in the lid. The base lines of the two tongues are of substantially the same size and are located parallel with and close to one another in such a manner that a narrow portion of the end plate is formed between the two tongues.